The present invention relates to a two-dimensional code recognition processing method, a two-dimensional code recognition processing apparatus, and a two-dimensional code recognition processing program storage medium. More particularly, the invention relates to a two-dimensional code recognition processing method, a two-dimensional code recognition processing apparatus, and a two-dimensional code recognition processing program storage medium for permitting efficient and accurate recognition of expanded code data made of a plurality of suitably captured two-dimensional codes in combination.
The so-called bar code system is used extensively in various industrial fields. The system involves encoding in bars alphanumeric characters representing types and conditions of goods and articles, and typically attaching such codes to the goods and articles so that the codes may be scanned later for retrieval of relevant information (e.g., about their types and conditions).
FIG. 23 shows a so-called one-dimensional bar code. In this example, a one-dimensional bar code label 500 is made up of a code part 501 and an ID (identification number) part 502. The code part 501 includes a combination of different widths of bars (in black) and bar-to-bar spaces (blanks). The ID part 502 indicates a code contained in the code part 501. Specifically, the ID part 502 shows as readable information alphanumeric characters that are coded in the code part 501. This type of one-dimensional bar code 500 is read by an optical recognition apparatus called a bar code scanner for recognition.
One way of reading the above-described one-dimensional bar code 500 is by use of a CCD video camera. As more and more bars are arranged to accommodate growing volumes of coded information, however, it becomes increasingly difficult for the CCD video camera to properly read such one-dimensional bar codes 500.
The difficulty in capturing large amounts of bar-coded information with the video camera is solved by a two-dimensional code system proposed to replace the one-dimensional bar code. As depicted in FIG. 24, various kinds of two-dimensional codes 600 have been proposed, each code comprising a code part 601 and an ID part 602. The code part 601 has a plurality of black square cells arranged two-dimensionally according to predetermined layout rules. The ID part 602 indicates a code that is contained in the code part 601.
Greater quantities of information are represented when the information is coded two-dimensionally than if the one-dimensional code 500 is used. In other words, it is easier for the video camera to read larger quantities of information if the information is coded two-dimensionally rather than one-dimensionally.
However, the two-dimensional code 600 has one disadvantage. That is, when the video camera picks up an image of a two-dimensional code 600 for code recognition, it is often difficult to distinguish the code from smear, dirt or other distracting images picked up nearby. The result is that code data are often difficult to recognize precisely.
In addition, only the code data assigned to each single two-dimensional code 600 has been usable in a related art, which poses constraints on the quantity of information made available for identification purposes. The limited scope of ID information availability in turn has restricted the scope of applications.